using System;
using System.Diagnostics;
using ByteScout.DocumentParser;

// This example demonstrates document data parsing to JSON, YAML and XML formats.

namespace HL7CreationFromJson
{
    class Program
    {
        static void Main(string[] args)
        {
            // Step 1: Generate Parse PDF File With Template and Generate Json
            string inputPDF = "InputData/Test_Report_Format.pdf";
            string template = "InputData/TestReportFormat.yml";

            // Create Document Parser Instance
            DocumentParser docParser = new DocumentParser("demo", "demo");

            // Add Template
            docParser.AddTemplate(template);

            // Parse document data in JSON format
            string jsonString = docParser.ParseDocument(inputPDF, OutputFormat.JSON);

            // Step 2: Parse Json fileds in class format
            var oInpModel = JsonParserHelper.ParseJsonHL7Fields(jsonString);

            // Step 3: Get Data in HL7 Format
            var oHL7Format = Hl7Helper.GetHL7Format(oInpModel);

            // Store HL7 File and open with default associated program
            var outputFile = "outputHl7.txt";
            System.IO.File.WriteAllText(outputFile, oHL7Format);
            Process.Start(outputFile);
        }
    }
}

using HL7.Dotnetcore;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace HL7CreationFromJson
{
    class Hl7Helper
    {
        /// <summary>
        /// Get HL7 format representation from input model
        /// </summary>
        public static string GetHL7Format(JsonHL7Fields inpModel)
        {
            // https://github.com/Efferent-Health/HL7-dotnetcore
            // http://www.j4jayant.com/2013/05/hl7-parsing-in-csharp.html

            Message oHl7Message = new Message();

            // Add MSH Segment
            Segment mshSegment = new Segment("MSH", new HL7Encoding());
            mshSegment.AddNewField("SendingApp", 3);
            mshSegment.AddNewField(inpModel.LabName ?? "", 4);
            mshSegment.AddNewField(DateTime.Now.ToString("yyyymmddhhMMss"), 7);
            mshSegment.AddNewField("ORM", 9); // Message type
            mshSegment.AddNewField("2.3", 12); // Message version
            oHl7Message.AddNewSegment(mshSegment);

            // Add PID Segment
            Segment pidSegment = new Segment("PID", new HL7Encoding());
            pidSegment.AddNewField("1", 1);
            pidSegment.AddNewField(inpModel.PatientChartNo ?? "", 2); // Patient ID
            pidSegment.AddNewField(inpModel.PatientChartNo ?? "", 4); // Alternate Patient ID
            pidSegment.AddNewField($"{inpModel.PatientLastName ?? ""}^{inpModel.PatientFirstName ?? ""}", 5); // Patient Name
            pidSegment.AddNewField(inpModel.PatientDOB ?? "", 7); // Patient DOB
            pidSegment.AddNewField(inpModel.PatientGender ?? "", 8); // Patient Gender
            pidSegment.AddNewField(inpModel.PatientAddress ?? "", 11); // Patient Address
            pidSegment.AddNewField(inpModel.PatientPhoneHome ?? "", 13); // Patient Home Phone number
            pidSegment.AddNewField(inpModel.PatientSSN ?? "", 19); // Patient SSN Number
            oHl7Message.AddNewSegment(pidSegment);

            // Add PV1 Segment
            Segment pv1Segment = new Segment("PV1", new HL7Encoding());
            pv1Segment.AddNewField($"{inpModel.PhysicianNpi ?? ""}^{inpModel.PhysicianName}", 7); // Physician information
            oHl7Message.AddNewSegment(pv1Segment);

            // Add IN1 Segment
            Segment in1Segment = new Segment("IN1", new HL7Encoding());
            in1Segment.AddNewField("1", 1);
            in1Segment.AddNewField(inpModel.InsuranceName ?? "", 4); // Insurance Name
            in1Segment.AddNewField(inpModel.InsuranceGroup ?? "", 8); // Insurance Group Name
            in1Segment.AddNewField(inpModel.InsuredName ?? "", 16); // Insured Name
            in1Segment.AddNewField(inpModel.RelationToPatient ?? "", 17); // Insured Relatino
            in1Segment.AddNewField(inpModel.InsuredDob ?? "", 18); // Insured Date of Birth
            in1Segment.AddNewField(inpModel.InsurancePolicy ?? "", 36); // Insurance Policy Number
            oHl7Message.AddNewSegment(in1Segment);

            // Add ORC Segment
            Segment orcSegment = new Segment("ORC", new HL7Encoding());
            orcSegment.AddNewField("NW", 1); // New Order
            orcSegment.AddNewField(inpModel.CollectionDateTime ?? "", 9); // Date/Time of Transaction
            orcSegment.AddNewField($"{inpModel.PhysicianNpi ?? ""}^{inpModel.PhysicianName ?? ""}", 12); // Ordering Provider
            oHl7Message.AddNewSegment(orcSegment);

            // Add OBR Segment
            Segment obrSegment = new Segment("OBR", new HL7Encoding());
            obrSegment.AddNewField(inpModel.CollectionDateTime ?? "", 7); // Date/Time of Transaction
            obrSegment.AddNewField($"{inpModel.PhysicianNpi ?? ""}^{inpModel.PhysicianName ?? ""}", 16); // Ordering Provider
            oHl7Message.AddNewSegment(obrSegment);

            // Add Diagnosis
            for (int i = 0; i < inpModel.Icd10Codes.Count; i++)
            {
                Segment dg1Segment = new Segment("DG1", new HL7Encoding());
                dg1Segment.AddNewField((i + 1).ToString(), 1);
                dg1Segment.AddNewField("I10", 2); // Icd Type
                dg1Segment.AddNewField(inpModel.Icd10Codes[i], 3); // Icd Code
                oHl7Message.AddNewSegment(dg1Segment);
            }

            // Add OBX
            for (int i = 0; i < inpModel.QuestionAnswer.Count; i++)
            {
                Segment obxSegment = new Segment("OBX", new HL7Encoding());
                obxSegment.AddNewField((i + 1).ToString(), 1);
                obxSegment.AddNewField("ST", 2); // Value Type
                obxSegment.AddNewField(inpModel.QuestionAnswer[i].Key, 3); // Question
                obxSegment.AddNewField(inpModel.QuestionAnswer[i].Value, 5); // Answer
                oHl7Message.AddNewSegment(obxSegment);
            }

            string oRetMessage = oHl7Message.SerializeMessage(false);

            return oRetMessage;
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace HL7CreationFromJson
{
    public class JsonHL7Fields
    {
        public JsonHL7Fields()
        {
            Icd10Codes = new List<string>();
            QuestionAnswer = new List<KeyValuePair<string, string>>();
        }

        public string LabName { get; set; }

        public string PatientLastName { get; set; }
        public string PatientFirstName { get; set; }
        public string PatientSSN { get; set; }
        public string PatientDOB { get; set; }
        public string PatientPhoneHome { get; set; }
        public string PatientPhoneWork { get; set; }
        public string PatientChartNo { get; set; }
        public string PatientGender { get; set; }
        public string PatientAddress { get; set; }

        public string PhysicianName { get; set; }
        public string PhysicianAccountNo { get; set; }
        public string PhysicianNpi { get; set; }

        public string InsuranceName { get; set; }
        public string InsurancePolicy { get; set; }
        public string InsuranceGroup { get; set; }
        public string InsuredName { get; set; }
        public string InsuredSSN { get; set; }
        public string InsuredDob { get; set; }
        public string RelationToPatient { get; set; }

        public string CollectionDateTime { get; set; }

        public List<string> Icd10Codes { get; set; }
        public List<KeyValuePair<string, string>> QuestionAnswer { get; set; }

    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Newtonsoft.Json.Linq;

namespace HL7CreationFromJson
{
    class JsonParserHelper
    {
        /// <summary>
        /// Parse Json Fileds in class format
        /// </summary>
        public static JsonHL7Fields ParseJsonHL7Fields(string jsonData)
        {
            // Get Object data from input file
            JObject jsonObj = JObject.Parse(jsonData);

            var oRet = new JsonHL7Fields();

            oRet.LabName = Convert.ToString(jsonObj["fields"]["labName"]["value"]);

            oRet.PatientLastName = Convert.ToString(jsonObj["fields"]["patientLastName"]["value"]);
            oRet.PatientFirstName = Convert.ToString(jsonObj["fields"]["patientFirstName"]["value"]);
            oRet.PatientSSN = Convert.ToString(jsonObj["fields"]["patientSSN"]["value"]);
            oRet.PatientDOB = Convert.ToString(jsonObj["fields"]["patientDOB"]["value"]);
            oRet.PatientPhoneHome = Convert.ToString(jsonObj["fields"]["patientHomePhone"]["value"]);
            oRet.PatientPhoneWork = Convert.ToString(jsonObj["fields"]["patientWorkPhone"]["value"]);
            oRet.PatientAddress = Convert.ToString(jsonObj["fields"]["patientAddress"]["value"]);
            oRet.PatientChartNo = Convert.ToString(jsonObj["fields"]["patientChartNo"]["value"]);

            string patGenderMaleSelectedVal = Convert.ToString(jsonObj["fields"]["patientGenderMale"]["value"]);
            string patGenderFemaleSelectedVal = Convert.ToString(jsonObj["fields"]["patientGenderFemale"]["value"]);

            if (!string.IsNullOrEmpty(patGenderMaleSelectedVal))
            {
                oRet.PatientGender = "M";
            }
            else if (!string.IsNullOrEmpty(patGenderFemaleSelectedVal))
            {
                oRet.PatientGender = "F";
            }

            oRet.PhysicianName = Convert.ToString(jsonObj["fields"]["physicianName"]["value"]);
            oRet.PhysicianAccountNo = Convert.ToString(jsonObj["fields"]["physicianAccountName"]["value"]);
            oRet.PhysicianNpi = Convert.ToString(jsonObj["fields"]["physicianNPI"]["value"]);

            oRet.InsuranceName = Convert.ToString(jsonObj["fields"]["insuranceName"]["value"]);
            oRet.InsurancePolicy = Convert.ToString(jsonObj["fields"]["insurancePolicy"]["value"]);
            oRet.InsuranceGroup = Convert.ToString(jsonObj["fields"]["insuranceGroup"]["value"]);
            oRet.InsuredName = Convert.ToString(jsonObj["fields"]["insuredName"]["value"]);
            oRet.InsuredSSN = Convert.ToString(jsonObj["fields"]["insuredSSN"]["value"]);
            oRet.InsuredDob = Convert.ToString(jsonObj["fields"]["insuredDOB"]["value"]);

            string relToPatIsSelf = Convert.ToString(jsonObj["fields"]["relationToPatientIsSelf"]["value"]);
            string relToPatIsSpouse = Convert.ToString(jsonObj["fields"]["relationToPatientIsSpouse"]["value"]);
            string relToPatIsDependent = Convert.ToString(jsonObj["fields"]["relationToPatientIsDependent"]["value"]);

            if (!string.IsNullOrEmpty(relToPatIsSelf))
            {
                oRet.RelationToPatient = "Self";
            }
            else if (!string.IsNullOrEmpty(relToPatIsSpouse))
            {
                oRet.RelationToPatient = "Spouse";
            }
            else if (!string.IsNullOrEmpty(relToPatIsDependent))
            {
                oRet.RelationToPatient = "Dependent";
            }

            // Add Collection Date/Time
            string colDate = Convert.ToString(jsonObj["fields"]["collectionDate"]["value"]);
            string colTime = Convert.ToString(jsonObj["fields"]["collectionTime"]["value"]);
            string colTimeIsAm = Convert.ToString(jsonObj["fields"]["collectionTimeIsAM"]["value"]);
            string colTimeIsPm = Convert.ToString(jsonObj["fields"]["collectionTimeIsPM"]["value"]);

            string colTimeAmPm = "";
            if (!string.IsNullOrEmpty(colTimeIsAm))
            {
                colTimeAmPm = "AM";
            }
            else if (!string.IsNullOrEmpty(colTimeIsPm))
            {
                colTimeAmPm = "PM";
            }

            oRet.CollectionDateTime = $"{colDate} {colTime} {colTimeAmPm}";


            // Add ICD Codes
            string IcdCodes = Convert.ToString(jsonObj["fields"]["icD10DxCodes"]["value"]);
            if (!string.IsNullOrEmpty(IcdCodes))
            {
                var arrIcdCodes = IcdCodes.Split(',');

                foreach (var itmIcd in arrIcdCodes)
                {
                    oRet.Icd10Codes.Add(itmIcd.Trim());
                }
            }

            // Add Question/Answers
            string Ques_ClinicalHistoryIsRoutinePap = string.IsNullOrEmpty(Convert.ToString(jsonObj["fields"]["clinicalHistoryIsRoutinePap"]["value"])) ? "No" : "Yes";
            string Ques_ClinicalHistoryIsAbnormalBleeding = string.IsNullOrEmpty(Convert.ToString(jsonObj["fields"]["clinicalHistoryIsAbnormalBleeding"]["value"])) ? "No" : "Yes";

            oRet.QuestionAnswer.Add(new KeyValuePair<string, string>("Is Routine PAP?", Ques_ClinicalHistoryIsRoutinePap));
            oRet.QuestionAnswer.Add(new KeyValuePair<string, string>("Is Abnormal Bleeding?", Ques_ClinicalHistoryIsAbnormalBleeding));

            return oRet;
        }

    }
}

using System;
using System.Collections.Generic;

/// <summary>
/// https://github.com/Efferent-Health/HL7-dotnetcore
/// </summary>
namespace HL7.Dotnetcore
{
    public class Component : MessageElement
    {
        internal List<SubComponent> SubComponentList { get; set; }

        public bool IsSubComponentized { get; set; } = false;

        private bool isDelimiter = false;

        public Component(HL7Encoding encoding, bool isDelimiter = false)
        {
            this.isDelimiter = isDelimiter;
            this.SubComponentList = new List<SubComponent>();
            this.Encoding = encoding;
        }
        public Component(string pValue, HL7Encoding encoding)
        {
            this.SubComponentList = new List<SubComponent>();
            this.Encoding = encoding;
            this.Value = pValue;
        }

        protected override void ProcessValue()
        {
            List<string> allSubComponents;

            if (this.isDelimiter)
                allSubComponents = new List<string>(new [] {this.Value});
            else
                allSubComponents = MessageHelper.SplitString(_value, this.Encoding.SubComponentDelimiter);

            if (allSubComponents.Count > 1)
            {
                this.IsSubComponentized = true;
            }

            this.SubComponentList = new List<SubComponent>();

            foreach (string strSubComponent in allSubComponents)
            {
                SubComponent subComponent = new SubComponent(this.Encoding.Decode(strSubComponent), this.Encoding);
                SubComponentList.Add(subComponent);
            }
        }

        public SubComponent SubComponents(int position)
        {
            position = position - 1;
            SubComponent sub = null;

            try
            {
                sub = SubComponentList[position];
            }
            catch (Exception ex)
            {
                throw new HL7Exception("SubComponent not availalbe Error-" + ex.Message);
            }

            return sub;
        }

        public List<SubComponent> SubComponents()
        {
            return SubComponentList;
        }
    }

    internal class ComponentCollection : List<Component>
    {
        /// <summary>
        /// Component indexer
        /// </summary>
        internal new Component this[int index]
        {
            get
            {
                Component component = null;

                if (index < base.Count)
                    component = base[index];

                return component;
            }
            set
            {
                base[index] = value;
            }
        }

        /// <summary>
        /// Add Component at next position
        /// </summary>
        /// <param name="component">Component</param>
        internal new void Add(Component component)
        {
            base.Add(component);
        }

        /// <summary>
        /// Add component at specific position
        /// </summary>
        /// <param name="component">Component</param>
        /// <param name="position">Position</param>
        internal void Add(Component component, int position)
        {
            int listCount = base.Count;
            position = position - 1;

            if (position < listCount)
            {
                base[position] = component;
            }
            else
            {
                for (int comIndex = listCount; comIndex < position; comIndex++)
                {
                    Component blankComponent = new Component(component.Encoding);
                    blankComponent.Value = string.Empty;
                    base.Add(blankComponent);
                }

                base.Add(component);
            }
        }
    }
}

using System;
using System.Globalization;
using System.Text;

/// <summary>
/// https://github.com/Efferent-Health/HL7-dotnetcore
/// </summary>
namespace HL7.Dotnetcore
{
    public class HL7Encoding
    {
        public string AllDelimiters { get; private set; } = @"|^~\&";
        public char FieldDelimiter { get; set; } = '|'; // \F\
        public char ComponentDelimiter { get; set; } = '^'; // \S\
        public char RepeatDelimiter { get; set; } = '~';  // \R\
        public char EscapeCharacter { get; set; } = '\\'; // \E\
        public char SubComponentDelimiter { get; set; } = '&'; // \T\
        public string SegmentDelimiter { get; set; } = "\r";
        public string PresentButNull { get; set; } = "\"\"";

        public HL7Encoding()
        {
        }

        public void EvaluateDelimiters(string delimiters)
        {
            this.FieldDelimiter = delimiters[0];
            this.ComponentDelimiter = delimiters[1];
            this.RepeatDelimiter = delimiters[2];
            this.EscapeCharacter = delimiters[3];
            this.SubComponentDelimiter = delimiters[4];
        }

        public void EvaluateSegmentDelimiter(string message)
        {
            string[] delimiters = new[] { "\r\n", "\n\r", "\r", "\n" };

            foreach (var delim in delimiters)
            {
                if (message.Contains(delim))
                {
                    this.SegmentDelimiter = delim;
                    return;
                }
            }

            throw new HL7Exception("Segment delimiter not found in message", HL7Exception.BAD_MESSAGE);
        }

        // Encoding methods based on https://github.com/elomagic/hl7inspector

        public  string Encode(string val)
        {
            if (val == null)
                return PresentButNull;

            if (string.IsNullOrWhiteSpace(val))
                return val;

            var sb = new StringBuilder();

            for (int i = 0; i < val.Length; i++) 
            {
                char c = val[i];

                if (c == this.ComponentDelimiter) {
                    sb.Append(this.EscapeCharacter);
                    sb.Append("S");
                    sb.Append(this.EscapeCharacter);
                } 
                else if (c == this.EscapeCharacter) {
                    sb.Append(this.EscapeCharacter);
                    sb.Append("E");
                    sb.Append(this.EscapeCharacter);
                } 
                else if (c == this.FieldDelimiter) {
                    sb.Append(this.EscapeCharacter);
                    sb.Append("F");
                    sb.Append(this.EscapeCharacter);
                } 
                else if (c == this.RepeatDelimiter) {
                    sb.Append(this.EscapeCharacter);
                    sb.Append("R");
                    sb.Append(this.EscapeCharacter);
                } 
                else if (c == this.SubComponentDelimiter) {
                    sb.Append(this.EscapeCharacter);
                    sb.Append("T");
                    sb.Append(this.EscapeCharacter);
                } 
                else if(c < 32) {
                    string v = string.Format("{0:X2}",(int)c);
                    if ((v.Length | 2) != 0) 
                        v = "0" + v;

                    sb.Append(this.EscapeCharacter);
                    sb.Append("X");
                    sb.Append(v);
                    sb.Append(this.EscapeCharacter);
                } 
                else {
                    sb.Append(c);
                }
            }

            return sb.ToString();
        }

        public string Decode(string encodedValue)
        {
            if (string.IsNullOrWhiteSpace(encodedValue))
                return encodedValue;

            var result = new StringBuilder();

            for (int i = 0; i < encodedValue.Length; i++)
            {
                char c = encodedValue[i];

                if (c != this.EscapeCharacter)
                {
                    result.Append(c);
                    continue;
                }

                i++;
                int li = encodedValue.IndexOf(this.EscapeCharacter, i);

                if (li == -1)
                    throw new HL7Exception("Invalid escape sequence in HL7 string");

                string seq = encodedValue.Substring(i, li-i);
                i = li;

                if (seq.Length == 0)
                    continue;

                switch (seq)
                {
                    case "H": // Start higlighting
                        result.Append("<B>");
                        break;
                    case "N": // normal text (end highlighting)
                        result.Append("</B>");
                        break;
                    case "F": // field separator
                        result.Append(this.FieldDelimiter);
                        break;
                    case "S": // component separator
                        result.Append(this.ComponentDelimiter);
                        break;
                    case "T": // subcomponent separator
                        result.Append(this.SubComponentDelimiter);
                        break;
                    case "R": // repetition separator
                        result.Append(this.RepeatDelimiter);
                        break;
                    case "E": // escape character
                        result.Append(this.EscapeCharacter);
                        break;
                    case ".br":
                        result.Append("<BR>");
                        break;
                    default:
                        if (seq.StartsWith("X"))
                            result.Append(((char)int.Parse(seq.Substring(1), NumberStyles.AllowHexSpecifier)));
                        else
                            result.Append(seq);
                        break;
                }
            }

            return result.ToString();
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;

/// <summary>
/// https://github.com/Efferent-Health/HL7-dotnetcore
/// </summary>
namespace HL7.Dotnetcore
{
    public class Field : MessageElement
    {
        private List<Field> _RepetitionList;

        internal ComponentCollection ComponentList { get; set; }

        public bool IsComponentized { get; set; } = false;
        public bool HasRepetitions { get; set; } = false;
        public bool IsDelimiters { get; set; } = false;

        internal List<Field> RepeatitionList
        {
            get
            {
                if (_RepetitionList == null)
                    _RepetitionList = new List<Field>();
                return _RepetitionList;
            }
            set
            {
                _RepetitionList = value;
            }
        }

        protected override void ProcessValue()
        {
            if (this.IsDelimiters)  // Special case for the delimiters fields (MSH)
            {
                var subcomponent = new SubComponent(_value, this.Encoding);

                this.ComponentList = new ComponentCollection();
                Component component = new Component(this.Encoding, true);

                component.SubComponentList.Add(subcomponent);

                this.ComponentList.Add(component);
                return;
            }

            this.HasRepetitions = _value.Contains(this.Encoding.RepeatDelimiter);

            if (this.HasRepetitions)
            {
                _RepetitionList = new List<Field>();
                List<string> individualFields = MessageHelper.SplitString(_value, this.Encoding.RepeatDelimiter);

                for (int index = 0; index < individualFields.Count; index++)
                {
                    Field field = new Field(individualFields[index], this.Encoding);
                    _RepetitionList.Add(field);
                }
            }
            else
            {
                List<string> allComponents = MessageHelper.SplitString(_value, this.Encoding.ComponentDelimiter);

                this.ComponentList = new ComponentCollection();

                foreach (string strComponent in allComponents)
                {
                    Component component = new Component(this.Encoding);
                    component.Value = strComponent;
                    this.ComponentList.Add(component);
                }

                this.IsComponentized = this.ComponentList.Count > 1;
            }
        }

        public Field(HL7Encoding encoding)
        {
            this.ComponentList = new ComponentCollection();
            this.Encoding = encoding;
        }

        public Field(string value, HL7Encoding encoding)
        {
            this.ComponentList = new ComponentCollection();
            this.Encoding = encoding;
            this.Value = value;
        }

        public bool AddNewComponent(Component com)
        {
            try
            {
                this.ComponentList.Add(com);
                return true;
            }
            catch (Exception ex)
            {
                throw new HL7Exception("Unable to add new component Error - " + ex.Message);
            }
        }

        public bool AddNewComponent(Component component, int position)
        {
            try
            {
                this.ComponentList.Add(component, position);
                return true;
            }
            catch (Exception ex)
            {
                throw new HL7Exception("Unable to add new component Error - " + ex.Message);
            }
        }

        public Component Components(int position)
        {
            position = position - 1;
            Component com = null;

            try
            {
                com = ComponentList[position];
            }
            catch (Exception ex)
            {
                throw new HL7Exception("Component not available Error - " + ex.Message);
            }

            return com;
        }

        public List<Component> Components()
        {
            return ComponentList;
        }

        public List<Field> Repetitions()
        {
            if (this.HasRepetitions)
            {
                return _RepetitionList;
            }
            return null;
        }

        public Field Repetitions(int repeatitionNumber)
        {
            if (this.HasRepetitions)
            {
                return _RepetitionList[repeatitionNumber - 1];
            }
            return null;
        }
    }

    internal class FieldCollection : List<Field>
    {
        internal new Field this[int index]
        {
            get
            {
                Field field = null;

                if (index < base.Count)
                    field = base[index];

                return field;
            }
            set
            {
                base[index] = value;
            }
        }

        /// <summary>
        /// add field at next position
        /// </summary>
        /// <param name="field">Field</param>
        internal new void Add(Field field)
        {
            base.Add(field);
        }

        /// <summary>
        /// Add field at specific position
        /// </summary>
        /// <param name="field">Field</param>
        /// <param name="position">position</param>
        internal void Add(Field field, int position)
        {
            int listCount = base.Count;

            if (position < listCount)
            {
                base[position] = field;
            }
            else
            {
                for (int fieldIndex = listCount; fieldIndex < position; fieldIndex++)
                {
                    Field blankField = new Field(string.Empty, field.Encoding);
                    base.Add(blankField);
                }

                base.Add(field);
            }
        }
    }
}

using System;

/// <summary>
/// https://github.com/Efferent-Health/HL7-dotnetcore
/// </summary>
namespace HL7.Dotnetcore
{
    public class HL7Exception : Exception
    {
        public const string REQUIRED_FIELD_MISSING = "Validation Error - Required field missing in message";
        public const string UNSUPPORTED_MESSAGE_TYPE = "Validation Error - Message Type Not Supported by this Implementation";
        public const string BAD_MESSAGE = "Validation Error - Bad Message";
        public const string PARSING_ERROR = "Parseing Error";
        public const string SERIALIZATION_ERROR = "Serialization Error";        

        public string ErrorCode { get; set; }

        public HL7Exception(string message) : base(message)
        {
        }

        public HL7Exception(string message, string Code) : base(message)
        {
            ErrorCode = Code;
        }

        public override string ToString()
        {
            return ErrorCode + " : " + Message;
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;

/// <summary>
/// https://github.com/Efferent-Health/HL7-dotnetcore
/// </summary>
namespace HL7.Dotnetcore
{
    public class Message
    {
        private List<string> allSegments = null;
        internal Dictionary<string, List<Segment>> SegmentList { get; set;} = new Dictionary<string, List<Segment>>();

        public string HL7Message { get; set; }
        public string Version { get; set; }
        public string MessageStructure { get; set; }
        public string MessageControlID { get; set; }
        public string ProcessingID { get; set; }
        public short SegmentCount { get; set; }
        public HL7Encoding Encoding { get; set; } = new HL7Encoding();

        public Message()
        {
        }

        public Message(string strMessage)
        {
            HL7Message = strMessage;
        }

        public override bool Equals(object obj)
        {
            if (obj is Message)
                return this.Equals((obj as Message).HL7Message);

            if (obj is string)
            {
                var arr1 = MessageHelper.SplitString(this.HL7Message, this.Encoding.SegmentDelimiter, StringSplitOptions.RemoveEmptyEntries);
                var arr2 = MessageHelper.SplitString(obj as string, this.Encoding.SegmentDelimiter, StringSplitOptions.RemoveEmptyEntries);

                return arr1.SequenceEqual(arr2);
            }

            return false;
        }

        public override int GetHashCode()
        {
            return this.HL7Message.GetHashCode();
        }

        /// <summary>
        /// Parse the HL7 message in text format, throws HL7Exception if error occurs
        /// </summary>
        /// <returns>boolean</returns>
        public bool ParseMessage()
        {
            bool isValid = false;
            bool isParsed = false;

            try
            {
                isValid = this.validateMessage();
            }
            catch (HL7Exception ex)
            {
                throw ex;
            }
            catch (Exception ex)
            {
                throw new HL7Exception("Unhandled Exception in validation - " + ex.Message, HL7Exception.BAD_MESSAGE);
            }

            if (isValid)
            {
                try
                {
                    if (this.allSegments == null || this.allSegments.Count <= 0)
                        this.allSegments = MessageHelper.SplitMessage(HL7Message);

                    short SegSeqNo = 0;

                    foreach (string strSegment in this.allSegments)
                    {
                        if (string.IsNullOrWhiteSpace(strSegment))
                            continue;

                        Segment newSegment = new Segment(this.Encoding);
                        string segmentName = strSegment.Substring(0, 3);
                        newSegment.Name = segmentName;
                        newSegment.Value = strSegment;
                        newSegment.SequenceNo = SegSeqNo++;

                        this.AddNewSegment(newSegment);
                    }

                    this.SegmentCount = SegSeqNo;

                    string strSerializedMessage = string.Empty;

                    try
                    {
                        strSerializedMessage = this.SerializeMessage(false); 
                    }
                    catch (HL7Exception ex)
                    {
                        throw new HL7Exception("Failed to serialize parsed message with error - " + ex.Message, HL7Exception.PARSING_ERROR);
                    }

                    if (!string.IsNullOrEmpty(strSerializedMessage))
                    {
                        if (this.Equals(strSerializedMessage))
                            isParsed = true;
                    }
                    else
                    {
                        throw new HL7Exception("Unable to serialize to original message - ", HL7Exception.PARSING_ERROR);
                    }
                }
                catch (Exception ex)
                {
                    throw new HL7Exception("Failed to parse the message with error - " + ex.Message, HL7Exception.PARSING_ERROR);
                }
            }

            return isParsed;
        }

        /// <summary>
        /// Serialize the message in text format
        /// </summary>
        /// <param name="validate">Validate the message before serializing</param>
        /// <returns>string with HL7 message</returns>
        public string SerializeMessage(bool validate)
        {
            if (validate && !this.validateMessage())
                throw new HL7Exception("Failed to validate the updated message", HL7Exception.BAD_MESSAGE);

            var strMessage = new StringBuilder();
            string currentSegName = string.Empty;
            List<Segment> _segListOrdered = getAllSegmentsInOrder();

            try
            {
                try
                {
                    foreach (Segment seg in _segListOrdered)
                    {
                        currentSegName = seg.Name;
                        strMessage.Append(seg.Name).Append(Encoding.FieldDelimiter);

                        int startField = currentSegName == "MSH" ? 1 : 0;

                        for (int i = startField; i<seg.FieldList.Count; i++)
                        {
                            if (i > startField)
                                strMessage.Append(Encoding.FieldDelimiter);

                            var field = seg.FieldList[i];

                            if (field.IsDelimiters)
                            {
                                strMessage.Append(field.Value);
                                continue;
                            }

                            if (field.HasRepetitions)
                            {
                                for (int j = 0; j < field.RepeatitionList.Count; j++)
                                {
                                    if (j > 0)
                                        strMessage.Append(Encoding.RepeatDelimiter);

                                    serializeField(field.RepeatitionList[j], strMessage);
                                }
                            }
                            else
                                serializeField(field, strMessage);
                        }

                        strMessage.Append(Encoding.SegmentDelimiter);
                    }
                }
                catch (Exception ex)
                {
                    if (currentSegName == "MSH")
                        throw new HL7Exception("Failed to serialize the MSH segment with error - " + ex.Message, HL7Exception.SERIALIZATION_ERROR);
                    else 
                        throw;
                }

                return strMessage.ToString();
            }
            catch (Exception ex)
            {
                throw new HL7Exception("Failed to serialize the message with error - " + ex.Message, HL7Exception.SERIALIZATION_ERROR);
            }
        }

        /// <summary>
        /// Get the Value of specific Field/Component/SubCpomponent, throws error if field/component index is not valid
        /// </summary>
        /// <param name="strValueFormat">Field/Component position in format SEGMENTNAME.FieldIndex.ComponentIndex.SubComponentIndex example PID.5.2</param>
        /// <returns>Value of specified field/component/subcomponent</returns>
        public string GetValue(string strValueFormat)
        {
            bool isValid = false;

            string segmentName = string.Empty;
            int fieldIndex = 0;
            int componentIndex = 0;
            int subComponentIndex = 0;
            int comCount = 0;
            string strValue = string.Empty;

            List<string> allComponents = MessageHelper.SplitString(strValueFormat, new char[] { '.' });
            comCount = allComponents.Count;

            isValid = validateValueFormat(allComponents);

            if (isValid)
            {
                segmentName = allComponents[0];

                if (SegmentList.ContainsKey(segmentName))
                {
                    if (comCount == 4)
                    {
                        Int32.TryParse(allComponents[1], out fieldIndex);
                        Int32.TryParse(allComponents[2], out componentIndex);
                        Int32.TryParse(allComponents[3], out subComponentIndex);

                        try
                        {
                            strValue = SegmentList[segmentName].First().FieldList[fieldIndex - 1].ComponentList[componentIndex - 1].SubComponentList[subComponentIndex - 1].Value;
                        }
                        catch (Exception ex)
                        {
                            throw new HL7Exception("SubComponent not available - " + strValueFormat + " Error: " + ex.Message);
                        }
                    }
                    else if (comCount == 3)
                    {
                        Int32.TryParse(allComponents[1], out fieldIndex);
                        Int32.TryParse(allComponents[2], out componentIndex);

                        try
                        {
                            strValue = SegmentList[segmentName].First().FieldList[fieldIndex - 1].ComponentList[componentIndex - 1].Value;
                        }
                        catch (Exception ex)
                        {
                            throw new HL7Exception("Component not available - " + strValueFormat + " Error: " + ex.Message);
                        }
                    }
                    else if (comCount == 2)
                    {
                        Int32.TryParse(allComponents[1], out fieldIndex);

                        try
                        {
                            strValue = SegmentList[segmentName].First().FieldList[fieldIndex - 1].Value;
                        }
                        catch (Exception ex)
                        {
                            throw new HL7Exception("Field not available - " + strValueFormat + " Error: " + ex.Message);
                        }
                    }
                    else
                    {
                        try
                        {
                            strValue = SegmentList[segmentName].First().Value;
                        }
                        catch (Exception ex)
                        {
                            throw new HL7Exception("Segment value not available - " + strValueFormat + " Error: " + ex.Message);
                        }
                    }
                }
                else
                {
                    throw new HL7Exception("Segment name not available: " + strValueFormat);
                }
            }
            else
            {
                throw new HL7Exception("Request format is not valid: " + strValueFormat);
            }

            return strValue;
        }

        /// <summary>
        /// Sets the Value of specific Field/Component/SubCpomponent, throws error if field/component index is not valid
        /// </summary>
        /// <param name="strValueFormat">Field/Component position in format SEGMENTNAME.FieldIndex.ComponentIndex.SubComponentIndex example PID.5.2</param>
        /// <param name="strValue">Value for the specified field/component</param>
        /// <returns>boolean</returns>
        public bool SetValue(string strValueFormat, string strValue)
        {
            bool isValid = false;
            bool isSet = false;

            string segmentName = string.Empty;
            int fieldIndex = 0;
            int componentIndex = 0;
            int subComponentIndex = 0;
            int comCount = 0;

            List<string> AllComponents = MessageHelper.SplitString(strValueFormat, new char[] { '.' });
            comCount = AllComponents.Count;

            isValid = validateValueFormat(AllComponents);

            if (isValid)
            {
                segmentName = AllComponents[0];
                if (SegmentList.ContainsKey(segmentName))
                {
                    if (comCount == 4)
                    {
                        Int32.TryParse(AllComponents[1], out fieldIndex);
                        Int32.TryParse(AllComponents[2], out componentIndex);
                        Int32.TryParse(AllComponents[3], out subComponentIndex);

                        try
                        {
                            SegmentList[segmentName].First().FieldList[fieldIndex - 1].ComponentList[componentIndex - 1].SubComponentList[subComponentIndex - 1].Value = strValue;
                            isSet = true;
                        }
                        catch (Exception ex)
                        {
                            throw new HL7Exception("SubComponent not available - " + strValueFormat + " Error: " + ex.Message);
                        }
                    }
                    else if (comCount == 3)
                    {
                        Int32.TryParse(AllComponents[1], out fieldIndex);
                        Int32.TryParse(AllComponents[2], out componentIndex);

                        try
                        {
                            SegmentList[segmentName].First().FieldList[fieldIndex - 1].ComponentList[componentIndex - 1].Value = strValue;
                            isSet = true;
                        }
                        catch (Exception ex)
                        {
                            throw new HL7Exception("Component not available - " + strValueFormat + " Error: " + ex.Message);
                        }
                    }
                    else if (comCount == 2)
                    {
                        Int32.TryParse(AllComponents[1], out fieldIndex);
                        try
                        {
                            SegmentList[segmentName].First().FieldList[fieldIndex - 1].Value = strValue;
                            isSet = true;
                        }
                        catch (Exception ex)
                        {
                            throw new HL7Exception("Field not available - " + strValueFormat + " Error: " + ex.Message);
                        }
                    }
                    else
                    {
                        throw new HL7Exception("Cannot overwrite a segment value");
                    }
                }
                else
                    throw new HL7Exception("Segment name not available");
            }
            else
                throw new HL7Exception("Request format is not valid");

            return isSet;
        }

        /// <summary>
        /// check if specified field has components
        /// </summary>
        /// <param name="strValueFormat">Field/Component position in format SEGMENTNAME.FieldIndex.ComponentIndex.SubComponentIndex example PID.5.2</param>
        /// <returns>boolean</returns>
        public bool IsComponentized(string strValueFormat)
        {
            bool isComponentized = false;
            bool isValid = false;

            string segmentName = string.Empty;
            int fieldIndex = 0;
            int comCount = 0;

            List<string> AllComponents = MessageHelper.SplitString(strValueFormat, new char[] { '.' });
            comCount = AllComponents.Count;

            isValid = validateValueFormat(AllComponents);

            if (isValid)
            {
                segmentName = AllComponents[0];
                if (comCount >= 2)
                {
                    try
                    {
                        Int32.TryParse(AllComponents[1], out fieldIndex);

                        isComponentized = SegmentList[segmentName].First().FieldList[fieldIndex - 1].IsComponentized;
                    }
                    catch (Exception ex)
                    {
                        throw new HL7Exception("Field not available - " + strValueFormat + " Error: " + ex.Message);
                    }
                }
                else
                    throw new HL7Exception("Field not identified in request");
            }
            else
                throw new HL7Exception("Request format is not valid");

            return isComponentized;
        }

        /// <summary>
        /// check if specified fields has repeatitions
        /// </summary>
        /// <param name="strValueFormat">Field/Component position in format SEGMENTNAME.FieldIndex.ComponentIndex.SubComponentIndex example PID.5.2</param>
        /// <returns>boolean</returns>
        public bool HasRepetitions(string strValueFormat)
        {
            bool hasRepetitions = false;
            bool isValid = false;

            string segmentName = string.Empty;
            int fieldIndex = 0;
            int comCount = 0;

            List<string> AllComponents = MessageHelper.SplitString(strValueFormat, new char[] { '.' });
            comCount = AllComponents.Count;

            isValid = validateValueFormat(AllComponents);

            if (isValid)
            {
                segmentName = AllComponents[0];
                if (comCount >= 2)
                {
                    try
                    {
                        Int32.TryParse(AllComponents[1], out fieldIndex);

                        hasRepetitions = SegmentList[segmentName].First().FieldList[fieldIndex - 1].HasRepetitions;
                    }
                    catch (Exception ex)
                    {
                        throw new HL7Exception("Field not available - " + strValueFormat + " Error: " + ex.Message);
                    }
                }
                else
                    throw new HL7Exception("Field not identified in request");
            }
            else
                throw new HL7Exception("Request format is not valid");

            return hasRepetitions;
        }

        /// <summary>
        /// check if specified component has sub components
        /// </summary>
        /// <param name="strValueFormat">Field/Component position in format SEGMENTNAME.FieldIndex.ComponentIndex.SubComponentIndex example PID.5.2</param>
        /// <returns>boolean</returns>
        public bool IsSubComponentized(string strValueFormat)
        {
            bool isSubComponentized = false;
            bool isValid = false;

            string segmentName = string.Empty;
            int fieldIndex = 0;
            int componentIndex = 0;
            int comCount = 0;

            List<string> AllComponents = MessageHelper.SplitString(strValueFormat, new char[] { '.' });
            comCount = AllComponents.Count;

            isValid = validateValueFormat(AllComponents);

            if (isValid)
            {
                segmentName = AllComponents[0];

                if (comCount >= 3)
                {
                    try
                    {
                        Int32.TryParse(AllComponents[1], out fieldIndex);
                        Int32.TryParse(AllComponents[2], out componentIndex);
                        isSubComponentized = SegmentList[segmentName].First().FieldList[fieldIndex - 1].ComponentList[componentIndex - 1].IsSubComponentized;
                    }
                    catch (Exception ex)
                    {
                        throw new HL7Exception("Component not available - " + strValueFormat + " Error: " + ex.Message);
                    }
                }
                else
                    throw new HL7Exception("Component not identified in request");
            }
            else
                throw new HL7Exception("Request format is not valid");

            return isSubComponentized;
        }

        /// <summary>
        /// Builds the acknowledgement message for this message
        /// </summary>
        /// <returns>An ACK message if success, otherwise null</returns>
        public Message GetACK()
        {
            return this.createAckMessage("AA", false, null);
        }

        /// <summary>
        /// Builds a negative ack for this message
        /// </summary>
        /// <param name="code">ack code like AR, AE</param>
        /// <param name="errMsg">Error message to be sent with NACK</param>
        /// <returns>A NACK message if success, otherwise null</returns>
        public Message GetNACK(string code, string errMsg)
        {
            return this.createAckMessage(code, true, errMsg);
        }

        /// <summary>
        /// Adds a segemnt to the message
        /// </summary>
        /// <param name="newSegment">Segment to be appended to the end of the message</param>
        /// <returns>True if added sucessfully, otherwise false</returns>
        public bool AddNewSegment(Segment newSegment)
        {
            try
            {
                newSegment.SequenceNo = SegmentCount++;

                if (!SegmentList.ContainsKey(newSegment.Name))
                    SegmentList[newSegment.Name] = new List<Segment>();

                SegmentList[newSegment.Name].Add(newSegment);
                return true;
            }
            catch (Exception ex)
            {
                SegmentCount--;
                throw new HL7Exception("Unable to add new segment. Error - " + ex.Message);
            }
        }

        /// <summary>
        /// Removes a segment from the message
        /// </summary>
        /// <param name="segmentName">Segment to be removed/param>
        /// <param name="index">Zero-based index of the sement to be removed, in case of multiple. Default is 0.</param>
        /// <returns>True if found and removed sucessfully, otherwise false</returns>
        public bool RemoveSegment(string segmentName, int index = 0) 
        {
            try
            {
                if (!SegmentList.ContainsKey(segmentName))
                    return false;

                var list = SegmentList[segmentName];
                if (list.Count <= index)
                    return false;

                list.RemoveAt(index);
                return true;
            }
            catch (Exception ex)
            {
                throw new HL7Exception("Unable to add remove segment. Error - " + ex.Message);
            }
        }

        public List<Segment> Segments()
        {
            return getAllSegmentsInOrder();
        }

        public List<Segment> Segments(string segmentName)
        {
            return getAllSegmentsInOrder().FindAll(o=> o.Name.Equals(segmentName));
        }

        public Segment DefaultSegment(string segmentName)
        {
            return getAllSegmentsInOrder().First(o => o.Name.Equals(segmentName));
        }

        /// <summary>
        /// Addsthe header segment to a new message
        /// </summary>
        /// <param name="sendingApplication">Sending application name</param>
        /// <param name="sendingFacility">Sending facility name</param>
        /// <param name="receivingApplication">Receiving application name</param>
        /// <param name="receivingFacility">Receiving facility name</param>
        /// <param name="security">Security features. Can be null.</param>
        /// <param name="messageType">Message type ^ trigger event</param>
        /// <param name="messageControlID">Message control unique ID</param>
        /// <param name="processingID">Processing ID ^ processing mode</param>
        /// <param name="version">HL7 message version (2.x)</param>
        public void AddSegmentMSH(string sendingApplication, string sendingFacility, string receivingApplication, string receivingFacility,
            string security, string messageType, string messageControlID, string processingID, string version)
        {
                var dateString = MessageHelper.LongDateWithFractionOfSecond(DateTime.Now);
                var delim = this.Encoding.FieldDelimiter;

                string response = "MSH" + this.Encoding.AllDelimiters + delim + sendingApplication + delim + sendingFacility + delim 
                    + receivingApplication + delim + receivingFacility + delim
                    + dateString + delim + (security ?? string.Empty) + delim + messageType + delim + messageControlID + delim 
                    + processingID + delim + version + this.Encoding.SegmentDelimiter;

                var message = new Message(response);
                message.ParseMessage();
                this.AddNewSegment(message.DefaultSegment("MSH"));
        }

        /// <summary>
        /// Serialize to MLLP escaped byte array
        /// </summary>
        /// <param name="validate">Optional. Validate the message before serializing</param>
        /// <returns>MLLP escaped byte array</returns>
        public byte[] GetMLLP(bool validate = false)
        {
            string hl7 = this.SerializeMessage(validate);

            return MessageHelper.GetMLLP(hl7);
        }

        /// <summary>
        /// Builds an ACK or NACK message for this message
        /// </summary>
        /// <param name="code">ack code like AA, AR, AE</param>
        /// <param name="isNack">true for generating a NACK message, otherwise false</param>
        /// <param name="errMsg">error message to be sent with NACK</param>
        /// <returns>An ACK or NACK message if success, otherwise null</returns>
        private Message createAckMessage(string code, bool isNack, string errMsg)
        {
            var response = new StringBuilder();

            if (this.MessageStructure != "ACK")
            {
                var dateString = MessageHelper.LongDateWithFractionOfSecond(DateTime.Now);
                var msh = this.SegmentList["MSH"].First();
                var delim = this.Encoding.FieldDelimiter;

                response.Append("MSH").Append(this.Encoding.AllDelimiters).Append(delim).Append(msh.FieldList[4].Value).Append(delim).Append(msh.FieldList[5].Value).Append(delim)
                    .Append(msh.FieldList[2].Value).Append(delim).Append(msh.FieldList[3].Value).Append(delim)
                    .Append(dateString).Append(delim).Append(delim).Append("ACK").Append(delim).Append(this.MessageControlID).Append(delim)
                    .Append(this.ProcessingID).Append(delim).Append(this.Version).Append(this.Encoding.SegmentDelimiter);

                response.Append("MSA").Append(delim).Append(code).Append(delim).Append(this.MessageControlID).Append((isNack ? delim + errMsg : string.Empty)).Append(this.Encoding.SegmentDelimiter);
            }
            else
            {
                return null;
            }

            try 
            {
                var message = new Message(response.ToString());
                message.ParseMessage();
                return message;
            }
            catch 
            {
                return null;
            }
        }

        /// <summary>
        /// Validates the HL7 message for basic syntax
        /// </summary>
        /// <returns>A boolean indicating whether the whole message is valid or not</returns>
        private bool validateMessage()
        {
            try
            {
                if (!string.IsNullOrEmpty(HL7Message))
                {
                    //check message length - MSH+Delimeters+12Fields in MSH
                    if (HL7Message.Length < 20)
                    {
                        throw new HL7Exception("Message Length too short: " + HL7Message.Length + " chars.", HL7Exception.BAD_MESSAGE);
                    }

                    //check if message starts with header segment
                    if (!HL7Message.StartsWith("MSH"))
                    {
                        throw new HL7Exception("MSH segment not found at the beggining of the message", HL7Exception.BAD_MESSAGE);
                    }

                    this.Encoding.EvaluateSegmentDelimiter(this.HL7Message);
                    this.HL7Message = string.Join(this.Encoding.SegmentDelimiter, MessageHelper.SplitMessage(this.HL7Message)) + this.Encoding.SegmentDelimiter;

                    //check Segment Name & 4th character of each segment
                    char fourthCharMSH = HL7Message[3];
                    this.allSegments = MessageHelper.SplitMessage(HL7Message);

                    foreach (string strSegment in this.allSegments)
                    {
                        if (string.IsNullOrWhiteSpace(strSegment))
                            continue;

                        bool isValidSegName = false;
                        string segmentName = strSegment.Substring(0, 3);
                        string segNameRegEx = "[A-Z][A-Z][A-Z1-9]";
                        isValidSegName = System.Text.RegularExpressions.Regex.IsMatch(segmentName, segNameRegEx);

                        if (!isValidSegName)
                        {
                            throw new HL7Exception("Invalid segment name found: " + strSegment, HL7Exception.BAD_MESSAGE);
                        }

                        char fourthCharSEG = strSegment[3];

                        if (fourthCharMSH != fourthCharSEG)
                        {
                            throw new HL7Exception("Invalid segment found: " + strSegment, HL7Exception.BAD_MESSAGE);
                        }
                    }

                    string _fieldDelimiters_Message = this.allSegments[0].Substring(3, 8 - 3);
                    this.Encoding.EvaluateDelimiters(_fieldDelimiters_Message);

                    // Count field separators, MSH.12 is required so there should be at least 11 field separators in MSH
                    int countFieldSepInMSH = this.allSegments[0].Count(f => f == Encoding.FieldDelimiter);

                    if (countFieldSepInMSH < 11)
                    {
                        throw new HL7Exception("MSH segment doesn't contain all the required fields", HL7Exception.BAD_MESSAGE);
                    }

                    // Find Message Version
                    var MSHFields = MessageHelper.SplitString(this.allSegments[0], Encoding.FieldDelimiter);

                    if (MSHFields.Count >= 12)
                    {
                        this.Version = MessageHelper.SplitString(MSHFields[11], Encoding.ComponentDelimiter)[0];
                    }
                    else
                    {
                        throw new HL7Exception("HL7 version not found in the MSH segment", HL7Exception.REQUIRED_FIELD_MISSING);
                    }

                    //Find Message Type & Trigger Event
                    try
                    {
                        string MSH_9 = MSHFields[8];

                        if (!string.IsNullOrEmpty(MSH_9))
                        {
                            var MSH_9_comps = MessageHelper.SplitString(MSH_9, this.Encoding.ComponentDelimiter);

                            if (MSH_9_comps.Count >= 3)
                            {
                                this.MessageStructure = MSH_9_comps[2];
                            }
                            else if (MSH_9_comps.Count > 0 && MSH_9_comps[0] != null && MSH_9_comps[0].Equals("ACK"))
                            {
                                this.MessageStructure = "ACK";
                            }
                            else if (MSH_9_comps.Count == 2)
                            {
                                this.MessageStructure = MSH_9_comps[0] + "_" + MSH_9_comps[1];
                            }
                            else
                            {
                                throw new HL7Exception("Message Type & Trigger Event value not found in message", HL7Exception.UNSUPPORTED_MESSAGE_TYPE);
                            }
                        }
                        else
                            throw new HL7Exception("MSH.10 not available", HL7Exception.UNSUPPORTED_MESSAGE_TYPE);
                    }
                    catch (System.IndexOutOfRangeException e)
                    {
                        throw new HL7Exception("Can't find message structure (MSH.9.3) - " + e.Message, HL7Exception.UNSUPPORTED_MESSAGE_TYPE);
                    }

                    try
                    {
                        this.MessageControlID = MSHFields[9];

                        if (string.IsNullOrEmpty(this.MessageControlID))
                            throw new HL7Exception("MSH.10 - Message Control ID not found", HL7Exception.REQUIRED_FIELD_MISSING);
                    }
                    catch (Exception ex)
                    {
                        throw new HL7Exception("Error occured while accessing MSH.10 - " + ex.Message, HL7Exception.REQUIRED_FIELD_MISSING);
                    }

                    try
                    {
                        this.ProcessingID = MSHFields[10];

                        if (string.IsNullOrEmpty(this.ProcessingID))
                            throw new HL7Exception("MSH.11 - Processing ID not found", HL7Exception.REQUIRED_FIELD_MISSING);
                    }
                    catch (Exception ex)
                    {
                        throw new HL7Exception("Error occured while accessing MSH.11 - " + ex.Message, HL7Exception.REQUIRED_FIELD_MISSING);
                    }
                }
                else
                    throw new HL7Exception("No Message Found", HL7Exception.BAD_MESSAGE);
            }
            catch (Exception ex)
            {
                throw new HL7Exception("Failed to validate the message with error - " + ex.Message, HL7Exception.BAD_MESSAGE);
            }

            return true;
        }

        /// <summary>
        /// Serializes a field into a string with proper encoding
        /// </summary>
        /// <returns>A serialized string</returns>
        private void serializeField(Field field, StringBuilder strMessage)
        {
            if (field.ComponentList.Count > 0)
            {
                int indexCom = 0;

                foreach (Component com in field.ComponentList)
                {
                    indexCom++;
                    if (com.SubComponentList.Count > 0)
                        strMessage.Append(string.Join(Encoding.SubComponentDelimiter.ToString(), com.SubComponentList.Select(sc => Encoding.Encode(sc.Value))));
                    else
                        strMessage.Append(Encoding.Encode(com.Value));

                    if (indexCom < field.ComponentList.Count)
                        strMessage.Append(Encoding.ComponentDelimiter);
                }
            }
            else
                strMessage.Append(Encoding.Encode(field.Value));

        }

        /// <summary> 
        /// Get all segments in order as they appear in original message. This the usual order: IN1|1 IN2|1 IN1|2 IN2|2
        /// </summary>
        /// <returns>A list of segments in the proper order</returns>
        private List<Segment> getAllSegmentsInOrder()
        {
            List<Segment> _list = new List<Segment>();

            foreach (string segName in SegmentList.Keys)
            {
                foreach (Segment seg in SegmentList[segName])
                {
                    _list.Add(seg);
                }
            }

            return _list.OrderBy(o => o.SequenceNo).ToList();
        }

        /// <summary>
        /// Validates the components of a value's position descriptor
        /// </summary>
        /// <returns>A boolean indicating whether all the components are valid or not</returns>
        private bool validateValueFormat(List<string> allComponents)
        {
            string segNameRegEx = "[A-Z][A-Z][A-Z1-9]";
            string otherRegEx = @"^[1-9]([0-9]{1,2})?$";
            bool isValid = false;

            if (allComponents.Count > 0)
            {
                if (Regex.IsMatch(allComponents[0], segNameRegEx))
                {
                    for (int i = 1; i < allComponents.Count; i++)
                    {
                        if (Regex.IsMatch(allComponents[i], otherRegEx))
                            isValid = true;
                        else
                            return false;
                    }
                }
                else
                {
                    isValid = false;
                }
            }

            return isValid;
        }
    }
}

/// <summary>
/// https://github.com/Efferent-Health/HL7-dotnetcore
/// </summary>
namespace HL7.Dotnetcore
{
    public abstract class MessageElement
    {
        protected string _value = string.Empty;


        public  string Value 
        { 
            get 
            {
                return _value == Encoding.PresentButNull ? null : _value; 
            }
            set 
            { 
                _value = value; 
                ProcessValue(); 
            }
        }

        public HL7Encoding Encoding { get; protected set; }

        protected abstract void ProcessValue();
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;

/// <summary>
/// https://github.com/Efferent-Health/HL7-dotnetcore
/// </summary>
namespace HL7.Dotnetcore
{
    public static class MessageHelper
    {
        private static string[] lineSeparators = { "\r\n", "\n\r", "\r", "\n" };

        public static List<string> SplitString(string strStringToSplit, string splitBy, StringSplitOptions splitOptions = StringSplitOptions.None)
        {
            return strStringToSplit.Split(new string[] { splitBy }, splitOptions).ToList();
        }

        public static List<string> SplitString(string strStringToSplit, char chSplitBy, StringSplitOptions splitOptions = StringSplitOptions.None)
        {
            return strStringToSplit.Split(new char[] { chSplitBy }, splitOptions).ToList();
        }

        public static List<string> SplitString(string strStringToSplit, char[] chSplitBy, StringSplitOptions splitOptions = StringSplitOptions.None)
        {
            return strStringToSplit.Split(chSplitBy, splitOptions).ToList();
        }

        public static List<string> SplitMessage(string message)
        {
            return message.Split(lineSeparators, StringSplitOptions.None).Where(m => !string.IsNullOrWhiteSpace(m)).ToList();
        }

        public static string LongDateWithFractionOfSecond(DateTime dt)
        {
            return dt.ToString("yyyyMMddHHmmss.FFFF");
        }

        public static string[] ExtractMessages(string messages)
        {
            var expr = "\x0B(.*?)\x1C\x0D";
            var matches = Regex.Matches(messages, expr, RegexOptions.Singleline);

            var list = new List<string>();
            foreach (Match m in matches)
                list.Add(m.Groups[1].Value);

            return list.ToArray();
        }

        public static DateTime? ParseDateTime(string dateTimeString, bool throwExeption = false)
        {
            return ParseDateTime(dateTimeString, out TimeSpan offset, throwExeption);
        }

        public static DateTime? ParseDateTime(string dateTimeString, out TimeSpan offset, bool throwExeption = false)
        {
            var expr = @"^\s*((?:19|20)[0-9]{2})(?:(1[0-2]|0[1-9])(?:(3[0-1]|[1-2][0-9]|0[1-9])(?:([0-1][0-9]|2[0-3])(?:([0-5][0-9])(?:([0-5][0-9](?:\.[0-9]{1,4})?)?)?)?)?)?)?(?:([+-][0-1][0-9]|[+-]2[0-3])([0-5][0-9]))?\s*$";
            var matches = Regex.Matches(dateTimeString, expr, RegexOptions.Singleline);

            try
            {
                if (matches.Count != 1)
                    throw new FormatException("Invalid date format");

                var groups = matches[0].Groups;
                int year = int.Parse(groups[1].Value);
                int month = groups[2].Success ? int.Parse(groups[2].Value) : 1;
                int day = groups[3].Success ? int.Parse(groups[3].Value) : 1;
                int hours = groups[4].Success ? int.Parse(groups[4].Value) : 0;
                int mins = groups[5].Success ? int.Parse(groups[5].Value) : 0;

                float fsecs = groups[6].Success ? float.Parse(groups[6].Value) : 0;
                int secs = (int)Math.Truncate(fsecs);
                int msecs = (int)Math.Truncate(fsecs * 1000) % 1000;

                int tzh = groups[7].Success ? int.Parse(groups[7].Value) : 0;
                int tzm = groups[8].Success ? int.Parse(groups[8].Value) : 0;
                offset = new TimeSpan(tzh, tzm, 0);

                return new DateTime(year, month, day, hours, mins, secs, msecs);
            }
            catch
            {
                if (throwExeption)
                    throw;

                offset = new TimeSpan();

                return null;
            }
        }

        /// <summary>
        /// Serialize string to MLLP escaped byte array
        /// </summary>
        /// <param name="message">String to serialize</param>
        /// <param name="encoding">Text encoder (optional)</param>
        /// <returns>MLLP escaped byte array</returns>
        public static byte[] GetMLLP(string message, Encoding encoding = null)
        {
            if (encoding == null)
                encoding = Encoding.UTF8;

            byte[] data = encoding.GetBytes(message);
            byte[] buffer = new byte[data.Length + 3];
            buffer[0] = 11;//VT

            Array.Copy(data, 0, buffer, 1, data.Length);
            buffer[buffer.Length - 2] = 28;//FS
            buffer[buffer.Length - 1] = 13;//CR

            return buffer;
        }
    }
}

using System;
using System.Collections.Generic;

/// <summary>
/// https://github.com/Efferent-Health/HL7-dotnetcore
/// </summary>
namespace HL7.Dotnetcore
{
    public class Segment : MessageElement
    {
        internal FieldCollection FieldList { get; set; }
        internal short SequenceNo { get; set; }

        public string Name { get; set; }

        public Segment(HL7Encoding encoding)
        {
            this.FieldList = new FieldCollection();
            this.Encoding = encoding;
        }

        public Segment(string name, HL7Encoding encoding)
        {
            this.FieldList = new FieldCollection();
            this.Name = name;
            this.Encoding = encoding;
        }

        protected override void ProcessValue()
        {
            List<string> allFields = MessageHelper.SplitString(_value, this.Encoding.FieldDelimiter);

            if (allFields.Count > 1)
            {
                allFields.RemoveAt(0);
            }

            for (int i = 0; i < allFields.Count; i++)
            {
                string strField = allFields[i];
                Field field = new Field(this.Encoding);   

                if (Name == "MSH" && i == 0)
                    field.IsDelimiters = true;  // special case

                field.Value = strField;
                this.FieldList.Add(field);
            }

            if (this.Name == "MSH")
            {
                var field1 = new Field(this.Encoding);
                field1.IsDelimiters = true;
                field1.Value = this.Encoding.FieldDelimiter.ToString();

                this.FieldList.Insert(0,field1);
            }
        }

        public Segment DeepCopy()
        {
            var newSegment = new Segment(this.Name, this.Encoding);
            newSegment.Value = this.Value; 

            return newSegment;        
        }

        public void AddEmptyField()
        {
            this.AddNewField(string.Empty);
        }

        public void AddNewField(string content, int position = -1)
        {
            this.AddNewField(new Field(content, this.Encoding), position);
        }

        public void AddNewField(string content, bool isDelimiters)
        {
            var newField = new Field(this.Encoding);

            if (isDelimiters)
                newField.IsDelimiters = true;   // Prevent decoding

            newField.Value = content;
            this.AddNewField(newField, -1);
        }

        public bool AddNewField(Field field, int position = -1)
        {
            try
            {
                if (position < 0)
                {
                    this.FieldList.Add(field);
                }
                else 
                {
                    position = position - 1;
                    this.FieldList.Add(field, position);
                }
                return true;
            }
            catch (Exception ex)
            {
                throw new HL7Exception("Unable to add new field in segment " + this.Name + " Error - " + ex.Message);
            }
        }

        public Field Fields(int position)
        {
            position = position - 1;
            Field field = null;

            try
            {
                field = this.FieldList[position];
            }
            catch (Exception ex)
            {
                throw new HL7Exception("Field not available Error - " + ex.Message);
            }

            return field;
        }

        public List<Field> GetAllFields()
        {
            return this.FieldList;
        }
    }
}

/// <summary>
/// https://github.com/Efferent-Health/HL7-dotnetcore
/// </summary>
namespace HL7.Dotnetcore
{
    public class SubComponent : MessageElement
    {
        public SubComponent(string val, HL7Encoding encoding)
        {
            this.Encoding = encoding;
            this.Value = val;
        }

        protected override void ProcessValue()
        {

        }
    }
}

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